Abstract:

The effect of light, lipase and lipoxygenase on lipid oxidation in frozen grass carp muscle during cold
storage was investigated. Acid value (AV), peroxide value (POV) and thiobarbituric acid reactive substances
(TBARs) were measured as indicators of lipid hydrolysis and initial and final lipid oxidation. During cold storage,
the hydrolysis and oxidation of lipids in fish muscle continued. Lipid hydrolysis in large quantities began on the 6th
and 4th days of storage in the light and in the dark, respectively, leading to the accumulation of large amounts of free
fatty acids. This was accompanied by the occurrence of lipid oxidation and thus the accumulation of large amounts
of hydrogen peroxide. The peroxide value (POV) reached maximum during storage on day 6 in the dark and on day
8 in the light. The TBARs value increased as the lipid oxidation continued. The POV and TBARs value became
significantly higher during storage in the light (P ＜ 0.05). Both lipase and lipoxygenase were able to considerably
accelerate the hydrolytic and oxidative degradation of lipids. In addition, this phenomenon and consequent lipid
deterioration were also observed during cold storage. Therefore, dark storage and enzyme inactivation can help
reduce the lipid oxidation in grass carp muscle during cold storage, maintain its high nutritive value and processing
quality and prolong its shelf life.

Key words: grass carp, fat, oxidation, hydrolysis, light, lipase, lipoxidase